CTI integration of telephonic calls moved between switches of an automatic call distributor

ABSTRACT

An apparatus and method are provided for identifying a call record of a telephone call to be moved from a source automatic call distributor to a destination automatic call distributor. The call record is of a type having been previously stored under a call identifier of the source automatic call distributor in a memory of the host computer serving both the source automatic call distributor and destination automatic call distributor in an area of the memory reserved for the source automatic call distributor. The method includes the step of storing a call action provided message in a call overflow table of the host computer including the call identifier of the telephone call and an identifier of the source automatic call distributor. The method further includes the step of transferring an overflow request to the destination automatic call distributor including the call identifier and searching the overflow table using the call identifier transferred to the destination automatic call distributor to locate the identifier of the source automatic call distributor. Finally, the method includes the step of locating the call record using the call identifier and located identifier of the source automatic call distributor.

This application is a continuation in part of U.S. Ser. No. 08/859,534,filed May 20, 1997.

FIELD OF THE INVENTION

The field of the invention relates to private branch exchange telephonesystems and in particular to tracking of calls moved from one automaticcall distributor to another automatic call distributor.

BACKGROUND OF THE INVENTION

Automatic call distribution systems are known. Such systems aretypically used in an organizational context within private branchtelephone exchanges (PBXs)as a means of distributing telephone callsamong a group of agents of the organization. While the automatic calldistributor (ACD) may be a separate part of the PBX, often the ACD isintegrated into and is an indistinguishable part of the PBX.

Often the organization disseminates a single telephone number to itscustomers and to the public in general as a means of contacting theorganization. As calls are directed to the organization from the publicswitch telephone network (PSTN), the automatic call distribution systemdirects the calls to its agents based upon some algorithm, typicallybased upon availability. For example, where all agents are considerequal, the ACD may distribute the calls based upon which agent position(telephone) has been idle the longest.

In order to distribute incoming calls from the PSTN to the availableagents, the interaction of a controlling computer with a switchingfabric of the PBX and ACD becomes essential. Often a connection to alocal PSTN is in the form of a number of trunk connections. Each of thetrunk connections is monitored by the controller for incoming calls.Where a call is detected, the controller searches for and selects anidle agent. Upon selecting an agent, the controller commands the switchto form a connection between the incoming trunk and selected agent.

In more complicated systems, the organization may use a number oftelephone numbers to identify different individuals and functions withinthe organization. Each telephone number may be assigned to a particularincoming trunk or group of incoming trunk lines. As such, the controllermay be required to recognize a call target based upon an identity of anincoming trunk line and route the call accordingly.

In other systems, the ACD of an organization may receive calls directedto different call targets over the same trunk lines. In such a case, thecall target may be identified to the ACD by a pulse code modulated (PCM)signal transferred from the PSTN to the controller of the ACD by adialed number identification service (DNIS) operating from within thePSTN.

In systems associated with service organizations, where many calls arereceived and handled by many agents, it may be important for an agent tohave ready access to customer files. In such a situation, a database ismaintained of existing customers. Customer records may be displayed onagent terminals as the agents converse with specific customers. In somecases, the customer may be identified to the database for display ofrecords on the terminal by the agent entering a customer identifier intoa keyboard associated with the terminal. Alternatively, the controllerof the ACD may transfer an identifier of the customer to the databasebased upon an automatic number identification (ANI) facility, operatingfrom within the PSTN.

Where ANI is used, the controller of the ACD receives the ANI digits(identifying the caller via the caller's telephone number) at the sametime the call arrives from the PSTN. Upon selecting an agent, thecontroller may transfer a call to a queue for the selected agent ordirectly to the selected agent. At the same time that the call isdelivered to the agent, the controller sends an identifier of theselected agent and ANI number of the customer to a controller of thedatabase (the host). The host, in turn, displays the customer recordsvia a computer monitor of the selected agent at the same time the callis delivered.

As a further feature, calls may be transferred among agents. Where afirst agent finds that he or she cannot help a particular customer, theagent may activate a key on a keyboard of the agent and may enter anidentity of another agent or agent group that may be better able to helpthe customer. The controller of the ACD may immediately connect the callto the newly identified agent, or may place the call in a queue untilthe identified agent becomes available.

In either case, the controller transfers a message to the hostidentifying the previous and newly identified agent. Since the hostknows the identity of the customer displayed at the terminal of theprevious agent, the host may now display those same customer records atthe terminal of the newly selected agent.

Where a call is placed in a queue, the ACD controller may monitor atotal time that the call has been in the queue. Where the time exceeds athreshold value, the controller may transfer (overflow) the call to anewly selected agent at another less heavily loaded ACD (overflow ACD)within the same organization. The controller of the transferring ACDtransfers DNIS and ANI information as well as a call sequence numberassigned by the transferring ACD to the overflow ACD. The overflow ACD,upon receiving the call, transfers the information to the host includingan identifier that the call is an overflow call. The host in turn thenpolls each ACD to identify the transferring ACD and any newly createdcall records created by the transferring ACD.

While the existing method of ACD operation is relatively satisfactory,it is dependent upon a record of connection transactions as a method ofidentifying a call to the host. Where a connection to an agent iscompleted, a transaction identifier is sent to the host memorializingthe transaction. The record of the connection is placed in a call recordheld in an area reserved for the transferring ACD. Where a call isreceived and placed in a queue for delivery to the next available agent,a call arrival message is sent to the host and saved in the transferringACD's record area. Where the call is then transferred to another ACD,there is no means for directly identifying the transferring ACD and thehost must poll each ACD to identify the call record of the call.Accordingly, a need exists for a better method of tracking overflowcalls among ACDs.

SUMMARY

An apparatus and method are provided for identifying a call record of atelephone call to be moved from a source automatic call distributor to adestination automatic call distributor. The call record is of a typehaving been previously stored under a call identifier of the sourceautomatic call distributor in a memory of the host computer serving boththe source automatic call distributor and destination automatic calldistributor in an area of the memory reserved for the source automaticcall distributor. The method includes the step of storing a call actionprovided message in a call overflow table of the host computer includingthe call identifier of the telephone call and an identifier of thesource automatic call distributor. The method further includes the stepof transferring an overflow request to the destination automatic calldistributor including the call identifier and searching the overflowtable using the call identifier transferred to the destination automaticcall distributor to locate the identifier of the source automatic calldistributor. Finally, the method includes the step of locating the callrecord using the call identifier and located identifier of the sourceautomatic call distributor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an automatic call distribution system in accordance withan embodiment of the invention;

FIG. 2 is a flow chart depicting the process of the system of FIG. 1;

FIG. 3 depicts a call arrival message used by the system of FIG. 1;

FIG. 4 depicts a call action provided message of the system of FIG. 1;and

FIG. 5 depicts an overflow arrival message of the system of FIG. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 is a block diagram of an automatic call distribution system 10 inaccordance with an embodiment of the invention. FIG. 2 is a flow chartof activity of the system 10 under the embodiment. Reference shall bemade to FIGS. 1 and 2 as appropriate to an understanding of theinvention.

Under the embodiment, a first, second and third internal network 11A,11B, 11C are connected to a host database computer 12 and the PSTN 16.Internal networks 11A, 11B, 11C may be located at geographically diverselocations and may be interconnected one-to-another by an appropriateinterconnecting group of private lines 17, 21 (e.g., leased lines,virtual private lines, microwave links, dedicated T1 lines, etc.).Similarly, the internal networks 11A, 11B, 11C may be interconnectedwith the host 12 through an appropriate data link (e.g., leased lines,virtual private lines, microwave link, the Internet, digital packetswitching, etc.).

The internal networks 11A, 11B, 11C may be connected to the PSTN 16through a number of trunk lines 19A, 19B, 19C. The PSTN 16 may offerservice on the trunk lines 19A, 19B 19C in association with servicessuch as ANI and DNIS. Call control, call maintenance, and call set-upmay be accomplished over the trunk line itself or over an associatedcontrol channel.

DNIS information supplied by the PSTN 16 is useful for the internalnetworks 11A, 11B, 11C where inbound calls to the internal networks 11A,11B, 11C may be directed to any of a large block of telephone numbersassigned to each of the internal networks 11A, 11B, 11C. This may beuseful where the block of numbers to the internal network (e.g., 11A) isconnected through the trunk lines 19A in rotary fashion, so that whenthe calling party from the PSTN appears, for example, on trunk T1, itcan be determined whether the calling party was, in fact, calling thetelephone number corresponding to trunk T1 or was, in fact, calling thetelephone number corresponding to trunk T2 and was rotated down to thenext available trunk, T1.

With regard to inbound calls, the switches 14A, 14B, 14C function toselectively interconnect calls from external customer units 15 of theexternal PSTN 16 to agents 18A, 18B, 18C of the internal networks 11A,11B, 11C. As such, each switch 14A, 14B, 14C functions as an automaticcall distributor within its own internal ACD network 11A, 11B, 11C.

The switches 14A, 14B, 14C are controlled by central processing units,or CPUs, 24A, 24B, 24C, in conjunction with peripheral memory devices26A, 26B, 26C. Control of the switches 11A, 11B, 11C and communicationswith the host 12 and PSTN 16 may be accomplished generally as describedin U.S. Pat. No. 5,268,903, and U.S. Pat. No. 5,140,611, both to Jones,and both incorporated herein by reference. Routing of calls to agents18A, 18B, 18C and overflow of calls may be accomplished generally asdescribed in: U.S. Pat. No. 5,335,269 to Steinlicht et al.; U.S. Pat.No. 5,365,581 to Baker et al.; and U.S. Pat. No. 5,384,841 to Adams etal., all incorporated herein by reference.

During operation, the CPUs 24A, 24B, 24C monitor 108 each port of theswitch 14A, 14B, 14C for changes in status. A change in status may be anagent unit 18A, 18B, 18C going off-hook to make a call 110, an agentunit 18A, 18B, 18C hanging up after a call 118, or it may be a callalerting tone detected on a trunk 19A, 19B, 19C alerting the CPU 24A,24B, 24C to the presence of an incoming call 110.

Where the status change is an agent 18A, 18B, 18C hanging up 118, theCPU 24A, 24B, 24C acts to tear-down the call connection within theswitch 14A, 14B, 14C between the agent at a first port of the switch anda second party to the conversation communicating through a second portof the switch 14A, 14B, 14C. Upon tear down of the connection, the CPU24A, 24B, 24C also sends a message to the host 120, notifying the hostof termination of the call connection. The message to the host 12 wouldinclude at least the identity of the agent 18A, 18B, 18C.

Where the status change is an agent 18A, 18B, 18C going offhook, the CPU24A, 24B, 24C interprets such change as preparation for the placement ofa telephone call. As such, the CPU 24A. 24B, 24C prepares to receive aset of dialed digits. Upon receiving the digits and if the digits aredetermined as being a call directed to an outside party, then the CPU24A, 24B, 24C may seize an outgoing trunk line 19A, 19B, 19C and send acall alert followed by the dialed digits. Where the alert is answered bya call connection acknowledgment, the CPU 24A, 24B, 24C completes theconnection between the port of the agent (e.g., 18A, 18B, 18C) and theport of the seized trunk line.

If the call is directed to another agent 18A, 18B, 18C or some otherparty within the organization, then the CPU 24A, 24B, 24C may identifythe port to which the calling party is to be connected by reference to alook-up table within memory 26A, 26B, 26C. Upon locating the party, theCPU 24A, 24B, 24C may then cause a connection to be set-up betweenappropriate ports within the switch 14A, 14B, 14C between the callingand called party.

Where the status change is a call alert signal on an incoming trunk line(or control channel associated with the incoming trunk line), then theCPU 24A, 24B, 24C may send an acknowledge message to the PSTN 16accepting the call. The PSTN 16 may respond with the forwarding of DNISand ANI messages, identifying the called and calling party.

Upon accepting the call, the CPU 24A, 24B, 24C first stores the DNIS andANI numbers in a termination table of the memory 26A, 26B, 26C. Morespecifically, the CPU 24A, 24B, 24C maintains a table of callinformation for each port of the switch 14A, 14B, 14C. Where a call isaccepted on an incoming trunk line, the CPU 24A, 24B, 24C enters theDNIS and ANI number into the table for the incoming trunk line uponwhich the call is received.

In addition to updating the termination table within memory 26A, 26B,26C, the CPU 24A, 24B, 24C also generates a call identifier (alsosometimes referred to as a call ID or sequence number) for the call,unique to the switch 14A, 14B, 14C. The call identifier along with theANI and DNIS numbers may then be sent 112 to the host 12 as part of acall arrival message. Delivery of the ANI and DNIS numbers and callidentifier allows the host 12 to create a unique call record for thecall in memory 28, in a call record area of memory 28 reserved for theswitch 14A. The call record may be used to retrieve customer records fordelivery to an appropriate display terminal 22A, 22B, 22C once the callhas been assigned to an agent 18A, 18B, 18C.

The CPU 24A, 24B, 24C then, by reference to the DNIS number, determinesthe identity of agent 18A, 18B, 18C to which the call is to be directed.For example, the DNIS number may be used to differentiate between callsdirected to a first telephone number arriving on a first incoming trunkgroup directed to a sales group of the organization from calls directedto a service group of the organization. Since agents servicing salescalls would, in most cases, not handle calls directed to service, theDNIS number provides a convenient means of differentiating between twoor more types of calls.

Upon determining the identity of the agent 18A, 18B, 18C (or group ofagents) the CPU 24A, 24B, 24C instructs the switch 14A, 14B, 14C tointernally connect the port of the incoming trunk to a port of one ofthe identified agents.

Where the call has been connected to an agent, the CPU 24A, 24B, 24Cstores the port number of the identified agent in the termination tablefor the port of the incoming trunk. Likewise, the CPU 24A, 24B, 24Cstores the port identifier of the incoming trunk in the terminationtable of the identified agent.

To complete set-up of the call to the identified agent, the CPU 24A,24B, 24C sends 116 a call completion message to the host 12. The callcompletion message includes at least a port identifier of the identifiedagent and the call identifier. The information of the call completionmessage is stored in the call record previously created in conjunctionwith arrival of the call arrival message. The port identifier and callidentifier allows the host 12 to deliver customer data to the specificdisplay terminal 22A, 22B, 22C of the agent to which the call wasdelivered.

In the alternative, if all of the agents (e.g., 18A) were busy, then anincoming call (e.g., received on incoming trunk T1 of the first switch14A) would be placed in a queue. While in the queue, the CPU 24A wouldcompare certain parameters of each call in the queue (e.g., time in thequeue) with a set of overflow threshold values. Where the parameters ofthe queued call exceed one or more of the overflow threshold values, thecall may be considered a candidate for overflow 122 to another switch.

In preparation for overflowing the call, the CPU 24A sends 128 a callaction provided (CAP) message (FIG. 4) to the host 12. The CAP messageis stored in a call overflow table in memory 28 for later reference inidentifying the original call record created by the first switch 14A.

In further preparation for overflow, the CPU 24A retrieves an identityof the next overflow destination (e.g., switch 14B) from a stack withinthe CPU 24A. Upon identifying the overflow destination, the CPU 24Aseizes an interconnect channel 17 through an interconnect port of theswitch 14A and forwards a transfer request over the interconnect 17between the source switch 14A and the destination switch 14B. While insome cases the CPU 24A may actually seize the interconnect channel 17,in other cases the CPU 24A may seize a control channel of theinterconnect 17A for transfer of the transfer request, followed by aseizing of the actual interconnect channel 17 the call is accepted. Thetransfer request may be under a pulse coded modulation (PCM) or anyother appropriate format. The transfer request may include at least fivedata fields. The first data field may identify the transmission as beinga transfer request. The second data field may identify the overflowdestination and the third field may be an identifier of the called party(e.g., DNIS digits) and of the calling party (e.g., ANI digits). Thelast field would include the call identifier assigned by the originalswitch 14A. The fifth field may include an identifier of thetransferring ACD 14A.

If the destination switch 14B accepts the call, a call accepted messageis returned over the interconnect 17. Upon receiving the call acceptmessage, the CPU 24A of the switch 14A instructs the switch 14A to forma connection between the incoming trunk port T1 and the interconnectport 17 for purposes of transferring the call.

If the destination switch 14B did not accept the call, then the CPU 24Amay retrieve the next potential overflow destination from the internalstack of the CPU 24A. The next overflow destination may be switch 14C.To execute the overflow, the CPU 24A may again seize an interconnect 17and transfer an overflow request.

Since the overflow request is not directed to the second switch 14B, theCPU 24B of the second switch 14B interprets the transmission as arequest for a connection between the first interconnect 17 an a secondinterconnect 21. The CPU 24B, in turn, instructs the switch 14B to forman internal connection between the first interconnect 17 and secondinterconnect 21.

Upon receipt of the request by the third switch 14C, the CPU 24C maydetermine that it can accept the transfer and returns a transferaccepted message through the connection within the second switch 14B tothe first switch 14A. Upon receiving the transfer accepted, the CPU 24Aof the first switch 14A instructs the switch 14A to form an internalconnection between the port of the incoming trunk T1 and the outgoinginterconnect 17. Since the connection through the second switch 14B isstill intact, the call received on the incoming trunk T1 at the firstswitch 14A has effectively been transferred to the third switch 14C.

The CPU 24C of the third switch 14C, at this point, knows the agentgroup requested by the call based upon the DNIS number within the callrequest. As a consequence, the third CPU 24C may place the call in aqueue and, at an appropriate instant, connect the call to a selectedagent 18C.

The CPU 24C, may also transfer the ANI digits of the caller to the host12 for purposes of identifying customer records. The host 12, however,does not know if it was the second switch 14B that originated thetransfer, or the first switch 14A. Further, since an identifier of thesource ACD 11A is not available to the host 12, the host cannot yetidentify the call record created by the first switch 14A.

The prior art has taught that for a switch to identify the source of thecall transfer, a polling operation must be performed on the otherswitches. The polling may be performed by transferring a request to thehost 12 requesting that each switch of the system 10 be polled to findout the identity of the switch 14A which directed a call transfer to thedestination switch 14C at that instant the destination switch 14Creceived the transfer request. The polling operation may be carried outby the host 12 sequentially searching the call records of each ACD 11A,11B, 11C.

Under the embodiment, the polling of switches 14A, 14B, 14C is avoidedthrough the transfer of a call action provided (CAP) message (FIG. 4),reserved for use in identifying calls arriving at an overflowdestination. The CAP message may be transferred to the host 12 beforethe transfer of a call. The CAP message is stored in an overflow tablewithin a memory 28 of the host 12, in an area not associated with anyparticular switch 14A, 14B, 14C.

In the example given above of a call transferred from an incoming trunkT1, the CAP message to the host 12 includes at least two fields. Thefirst field is an identifier 40 of the sending switch 14A. The secondfield is the call identifier 36 assigned by the source switch 14A. Athird optional field 42 is provided for identification of an agent 18A,in the case where the call has been answered by an agent 18A andsubsequently transferred.

When the destination switch 14C receives the call, the destinationswitch 14C assigns a new call identifier (new call ID) to the call. Thedestination switch 14C also sends a call arrival message (FIG. 5) to thehost 12. In this case, however, the destination switch does not have asufficient number of data fields in the call arrival message to sendboth the source switch ID and call identifier of the source ACD 11A.Instead, the destination switch 14C sends an indication 44 that the callis an overflow call, the call identifier 36 of the source switch 14A andthe new call ID 46 of the overflow call.

Upon receiving the call arrival message from the destination switch 14C,the host 12 searches an overflow table in memory 28 of the host 12 usingthe call identifier 36 assigned by the source switch 14A. Upon matchingthe call identifier 36 in the call overflow table, the host 12 is ableto find an identifier of the source switch 14A. Upon identifying thesource switch 14A, the host 12 in turn is able to search the callrecords of the source ACD 11A, identify and retrieve the call record(FIG. 3) and the ANI 32 of the customer. Upon identifying the properfile, the host 12 transfers the call record to the memory area of thedestination switch 14C. When the call is subsequently delivered to aselected agent 18C, the call record may now be used to simultaneouslydeliver customer records to the terminal display 22C of the selectedagent 18C.

Under another embodiment of the invention, calls may be moved from oneACD to another using the above-described call action provided messagethrough the PSTN 16. Under the embodiment, calls may be more properlyreferred to as having been moved because the call route to the ACDsystem 10 may be changed within the PSTN 16 as the call is moved from afirst ACD 11A to a second ACD 11B and also because the basis of the movemay be different from that used to characterize overflow.

Call moves may be desireable for any of a number of reasons. Calloverflow (due to capacity limitations) may be one reason, but iscertainly not the only reason. For instance, a call may be moved whereit is determined by a first ACD 11A that the first ACD 11A does not havethe appropriate (as opposed to sufficient) resources to handle the call.Such a case may arise where different ACDs of an ACD system 10 aregeared to handle different types of products.

Further, an agent at the first ACD 11A may already have discussed thecaller's problem with the caller and may have collected customerinformation from the caller in addition to the ANI and DNIS informationcollected by the ACD 10 from the PSTN 16 during call delivery. Theability to pass on any collected information with the call is beneficialbecause the information may be used to expedite call handling throughanother ACD.

Call movement within the PSTN 16 may be accomplished using any of anumber of processes. For example, call transfer may be used along withother features of the system 10 to accomplish a call move. Where theinterconnect 19A, 19B, 19C with the PSTN 16 is an ISDN connection, callmovement may be accomplished via instructions forwarded to the PSTN 16over the “D” channel associated with the incoming telephone call to bemoved.

To accomplish call movement from a first ACD 11A (i.e., the moving ACD)to a second ACD 11B (i.e., the destination ACD), the first ACD 11Atransmits a call forwarding instruction (message) to an ISDN controller(not shown) within the PSTN 16. Within the call forwarding message, afield is provided for a destination telephone number (e.g., the secondACD 11B).

Also included within the call forwarding message is a user-to-user dataelement (user field) that may be delivered along with the moved call.Within the user field, the moving ACD 11A may insert (among otherthings) an ACD identifier, identifying itself as the source ACD 11A andan indication to the destination ACD 11B that the associated call isbeing moved from the source ACD 11A to the destination ACD 11B. Alsoincluded in the user field may be other information such as the callidentifier assigned by the originating ACD 11A when it was received atthe originating ACD 11A.

Call moves may also be accomplished using non-ISDN lines. For example, afirst ACD 11A may request permission and may transfer identifyinginformation about the call over interconnect lines 17. Upon receivingpermission, the originating ACD 11A may transfer the call to thedestination ACD 11B through the PSTN 16.

For example, a flash-hook on the incoming connection may be used toplace the call on hold. A transfer number may be outpulsed to the PSTN16 over the line using pulse coded modulation (PCM). The PSTN 16 maythen transfer the call to the destination ACD 11B.

In general, call moves may be initiated for any of a number of reasons.The source ACD (e.g., 11A) may determine that the call is an overflowcandidate based upon any of a number of queuing parameters (e.g., timein queue). Alternatively, an agent receiving the call at a first ACD 11Amay determine (from the subject matter of the discussion with thecaller) that the call could be better handled through another ACD.

Where it is the agent who determines that the call should be moved, theagent may simply activate a TRANSFER button on the agent unit 18A.Following activation of the TRANSFER button, the agent may enter aspecific agent code, the code of another ACD (e.g., 11B) or a subjectmatter code.

In any case, the CPU 24A may (by reference to a look-up table) proceedto determine a route through which to move the call. Once a route hasbeen determined (or in some cases before), the CPU 24A transfers a CAPmessage (FIG. 4) to the host 12. The host 12 may store the CAP messagein an overflow table (or in the case of call moves), or in a (moregeneral) call move table (that may also be labeled a call actionprovided table).

Where the call is to be moved to another ACD (11B) through the PSTN 16,the CPU 24A also composes and forwards a call transfer request to thePSTN 16. Included as part of the call transfer request (transferred overthe “D” channel associated with the call to be moved) is a calldestination and the packet of user to user information. Within the userpacket may be five elements. The first element may identify the packetas a user-to-user transmission. The second element may be an indicationthat the transfer is a call move. The third element may be an identifierof the originally called party 11A (e.g., DNIS digits). The fourthelement may be the call identifier assigned by the originating ACD 11A.The last field may the ACD identifier of the transferring ACD 11A.

Once the PSTN 16 receives the call transfer request, the call is movedto the requested destination ACD 11B along with the user packet,included with the call transfer request. Once the call is received, thedestination ACD 11B composes a call arrival message (either the same orsimilar to that of FIG. 5) and transfers the message to the host 12.

Once received by the host 12, the host 12 searches the overflow table(or call action provided table, or call move table) for a messageindicating a call move. As above, the host 12 may identify the propercall action provided message by matching the call identifier received inthe user packet from the PSTN 16 with the call identifier assigned bythe originating ACD. Upon matching the call identifier of theoriginating ACD, the host 12 is able to identify the originating ACD.With a knowledge of the originating ACD and of the call identifierassigned by the originating ACD, the host 12 is now able to identify andretrieve the call record created by the originating ACD. Onceidentified, the call record may then be presented to an assigned agentat the destination ACD 11B through a terminal 22B of the assigned agent.

The use of the CAP message improves the speed and efficiency of the calloverflow and move operations by allowing the host 12 to quickly andeasily identify call records without the time consuming step ofsearching the call records of each ACD 11A, 11B, 11C. The use of the CAPmessage from the transferring ACD also provides the host 12 with a meansfor identifying overflow and moved calls on an exception basis ratherthan requiring a modification of the structure of the call arrivalmessage, which must be executed for each call.

A specific embodiment of a method and apparatus of overflowing andmoving calls according to the present invention has been described forthe purpose of illustrating the manner in which the invention is madeand used. It should be understood that the implementation of othervariations and modifications of the invention and its various aspectswill be apparent to one skilled in the art, and that the invention isnot limited by the specific embodiments described. Therefore, it iscontemplated to cover the present invention any and all modifications,variations, or equivalents that fall within the true spirit and scope ofthe basic underlying principles disclosed and claimed herein.

What is claimed is:
 1. A method of identifying a call record of atelephone call to be moved from a source automatic call distributor to adestination automatic call distributor, the call record having beenpreviously stored under a call identifier of the source automatic calldistributor in a memory of a host computer serving both the sourceautomatic call distributor and destination automatic call distributor inan area of the memory reserved for the source automatic calldistributor, such method comprising the steps of: storing a call actionprovided message in a call table of the host computer including the callidentifier of the telephone call and an identifier of the sourceautomatic call distributor; transferring a move request from the sourceautomatic call distributor to the destination automatic call distributorincluding the call identifier; searching the call table using the callidentifier transferred to the destination automatic call distributor tolocate the identifier of the source automatic call distributor; andlocating the call record using the call identifier and locatedidentifier of the source automatic call distributor.
 2. The method ofidentifying a call record of a telephone call to be moved from a sourceautomatic call distributor to a destination automatic call distributoras in claim 1 wherein the step of transferring the move request furthercomprises moving the call from the source automatic call distributor tothe destination call distributor through a public switched telephonenetwork.
 3. The method of identifying a call record of a telephone callto be moved as in claim 2 wherein the step of moving the call throughthe public switched telephone network further comprises transferring acall transfer request from the source automatic call distributor to thepublic switched telephone network.
 4. The method of identifying a callrecord of a telephone call to be moved as in claim 3 wherein the step ofmoving the call through the public switched telephone network furthercomprises transferring a user to user message to the destinationautomatic call distributor through the public switched telephonenetwork.
 5. The method of identifying a call record of a telephone callto be moved as in claim 4 wherein the step of transferring the user touser message to the destination automatic call distributor through thepublic switched telephone network further comprises including a callidentifier assigned by the source automatic call distributor in the userto user message.
 6. The method of identifying a call record of atelephone call to be moved as in claim 5 wherein the step oftransferring the user to user message to the destination automatic calldistributor through the public switched telephone network furthercomprises including an identifier of the source automatic calldistributor in the user to user message.
 7. The method of identifying acall record of a telephone call to be moved as in claim 3 wherein thestep of moving the call through the public switched telephone networkfurther comprises transferring a call move message to the destinationautomatic call distributor through an interconnect between the sourceand destination automatic call distributor.
 8. The method of identifyinga call record of a telephone call to be moved as in claim 7 wherein thestep of transferring the call move message to the destination automaticcall distributor through the interconnect further comprises including acall identifier assigned by the source automatic call distributor in theuser to user message.
 9. The method of identifying a call record of atelephone call to be moved as in claim 8 wherein the step oftransferring the call move message to the destination automatic calldistributor through the interconnect further comprises including anidentifier of the source automatic call distributor in the user to usermessage.
 10. The method of identifying a call record of a telephone callto be moved as in claim 1 wherein the step of locating the call recordusing the call identifier and located identifier of the source automaticcall distributor further comprises searching the area of the memoryreserved for the source automatic call distributor for the call recordstored under the call identifier.
 11. Apparatus for identifying a callrecord of a telephone call to be moved from a source automatic calldistributor to a destination automatic call distributor, the call recordhaving been previously stored under a call identifier of the sourceautomatic call distributor in a memory of a host computer serving boththe source automatic call distributor and destination automatic calldistributor in an area of the memory reserved for the source automaticcall distributor, such apparatus comprising: means for storing a callaction provided message in a call table of the host computer includingthe call identifier of the telephone call and an identifier of thesource automatic call distributor; means for transferring a move requestfrom the source automatic call distributor to the destination automaticcall distributor including the call identifier; means for searching thecall table using the call identifier transferred to the destinationautomatic call distributor to locate the identifier of the sourceautomatic call distributor; and means for locating the call record usingthe call identifier and located identifier of the source automatic calldistributor.
 12. The apparatus for identifying a call record of atelephone call to be moved from a source automatic call distributor to adestination automatic call distributor as in claim 11 wherein the meansfor transferring the move request further comprises means for moving thecall from the source automatic call distributor to the destination calldistributor through a public switched telephone network.
 13. Theapparatus for identifying a call record of a telephone call to be movedas in claim 12 wherein the means for moving the call through the publicswitched telephone network further comprises means for transferring acall transfer request from the source automatic call distributor to thepublic switched telephone network.
 14. The apparatus for identifying acall record of a telephone call to be moved as in claim 13 wherein themeans for moving the call through the public switched telephone networkfurther comprises means for transferring a user to user message to thedestination automatic call distributor through the public switchedtelephone network.
 15. The apparatus for identifying a call record of atelephone call to be moved as in claim 14 wherein the means fortransferring the user to user message to the destination automatic calldistributor through the public switched telephone network furthercomprises means for including a call identifier assigned by the sourceautomatic call distributor in the user to user message.
 16. Theapparatus for identifying a call record of a telephone call to be movedas in claim 15 wherein the means for transferring the user to usermessage to the destination automatic call distributor through the publicswitched telephone network further comprises means for including anidentifier of the source automatic call distributor in the user to usermessage.
 17. The apparatus for identifying a call record of a telephonecall to be moved as in claim 13 wherein the means for moving the callthrough the public switched telephone network further comprises meansfor transferring a call move message to the destination automatic calldistributor through an interconnect between the source and destinationautomatic call distributor.
 18. The apparatus for identifying a callrecord of a telephone call to be moved as in claim 17 wherein the meansfor transferring the call move message to the destination automatic calldistributor through the interconnect further comprises means forincluding a call identifier assigned by the source automatic calldistributor in the user to user message.
 19. The apparatus foridentifying a call record of a telephone call to be moved as in claim 18wherein the means for transferring the call move message to thedestination automatic call distributor through the interconnect furthercomprises means for including an identifier of the source automatic calldistributor in the user to user message.
 20. The apparatus foridentifying a call record of a telephone call to be moved as in claim 11wherein the means for locating the call record using the call identifierand located identifier of the source automatic call distributor furthercomprises means for searching the area of the memory reserved for thesource automatic call distributor for the call record stored under thecall identifier.
 21. Apparatus for identifying a call record of atelephone call to be moved from a source automatic call distributor to adestination automatic call distributor, the call record having beenpreviously stored under a call identifier of the source automatic calldistributor in a memory of a host computer serving both the sourceautomatic call distributor and destination automatic call distributor inan area of the memory reserved for the source automatic calldistributor, such apparatus comprising: a call action processor whichstores a call action provided message in a call table of the hostcomputer including the call identifier of the telephone call and anidentifier of the source automatic call distributor; a communicationprocessor which transfers a move request from the source automatic calldistributor to the destination automatic call distributor including thecall identifier; a search processor which searchs the call table usingthe call identifier transferred to the destination automatic calldistributor to locate the identifier of the source automatic calldistributor; and call record processor which locates the call recordusing the call identifier and located identifier of the source automaticcall distributor.
 22. The apparatus for identifying a call record of atelephone call to be moved from a source automatic call distributor to adestination automatic call distributor as in claim 21 wherein thecommunication processor which transfers the move request furthercomprises a control interface with a public switched telephone networkwhich moves the call from the source automatic call distributor to thedestination call distributor through the public switched telephonenetwork.
 23. The apparatus for identifying a call record of a telephonecall to be moved as in claim 22 wherein the control interface furthercomprises an ISDN interface.